Version 4
SHEET 1 1012 680
WIRE 128 80 -208 80
WIRE 128 144 128 80
WIRE 96 160 16 160
WIRE -208 176 -208 80
WIRE 288 176 160 176
WIRE 400 176 368 176
WIRE 96 192 -96 192
WIRE -96 208 -96 192
WIRE 128 256 128 208
WIRE 400 256 400 176
WIRE 16 272 16 160
WIRE -208 288 -208 256
WIRE -96 320 -96 288
WIRE 16 384 16 352
FLAG -208 288 0
FLAG 128 256 0
FLAG 400 256 0
FLAG -96 320 0
FLAG 16 384 0
SYMBOL voltage -208 160 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL voltage -96 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 2
SYMBOL voltage 16 256 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PWL(0 5 5 0)
SYMBOL res 384 160 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R1
SYMATTR Value 100k
SYMBOL Opamps\\opamp2 128 112 R0
SYMATTR InstName U1
SYMATTR Value LM239
SYMATTR SpiceModel LM239
TEXT -242 428 Left 0 !.tran 10
TEXT 296 408 Left 0 !.include LM239.mod